Ventilation devices are disclosed in WO 2004/035343 A1. These tank ventilation devices prevent penetrating contaminating media from the environment from being able to penetrate into the hydraulic system beginning with the tank, but prevent the required air exchange from being able to take place. Poorly designed reservoir ventilation could cause additional loading of the hydraulic system and, for example, could lead to shortened service lives of the system filters located in the hydraulic system. In particular the tank ventilation devices with their filters should efficiently precipitate solid particles from the air that may subsequently flow into the tank.
Tank and/or engine contaminants arising in practical use are usually eliminated by cleaning measures by steam jet devices under high pressure, with the consequence that penetrating media such as water and/or cleaning chemicals can enter the interior of the ventilation device and accordingly the interior of the tank. This event is extremely disadvantageous for the quality of the stored fluid in the tank, especially when dirt particles are flushed in at the same time via the fluid.